Suspension mechanism for sliding doors

ABSTRACT

A sliding door for a rapid transit type railway car is suspended from a track anchored only at its ends to the car body above a door opening. The track has a ridged base portion with a round bar seated in a groove in the apex of the ridge and secured to the base. A pair of sliding doors, each of a size to cover half the door opening, are each suspended from one of the tracks by a pair of open type, linear motion ball bearing hangers which are mounted one at each end of the top of each door and ride along the bar portion of their respective tracks. The bottoms of the doors clear the lower end of the door opening, and a downwardly open channel provided in the lower edge of each door receives roller guides mounted on the sill structure to firmly guide the door and restrain it against inward and outward displacement by lateral forces acting on the doors.

United States Patent [1 1 Bainbridge SUSPENSION NIECl-IANISM FOR SLIDINGDOORS [75] Inventor: Cecil Bainbridge, La Mesa, Calif. [73] Assignee:Rohr Industries, Inc., Chula Vista,

Calif. 22 Filed: Sept. 21, 1970 21 App1.No.: 74,045

[52] US. Cl .1 ..49/411, 49/370 [51] Int. Cl. ..E05d 13/02 [58] Field ofSearch, 49/409-411. 49/420, 425, 370, 360, 362; 16/87, 88, 91, 96

[5 6] References Cited UNITED STATES PATENTS 2,056,174 10/1936 Earhuffet a1 ..49/362 X 2,951,390 9/1960 Martens et a1 ..49/362 X 2,068,674H1937 Harvey ..l6/88 2,728,101 12/1955 Cowdroy ..l6/88 2,660,269 11/1953Whitehouse et a1. .....49/411 X 2,027,920 1/ 1936 Lindquist ..49/41 12,893,071 7/1959 Oden 16/96 1 Apr. 17, 1973 Primary Examiner-J. KarlBell Attorney-George E. Pearson ABSTRACT A sliding door for a rapidtransit type railway car is suspended from a track anchored only at itsends to the car body above a door opening. The track has a ridged baseportion with a round bar seated in a groove in the apex of the ridge andsecured to the base. A pair of sliding doors, each of a size to coverhalf the door opening, are each suspended from one of the tracks by 'apair of open type, linear motion ball bearing hangers which are mountedone at each end of the top of each door and ride along the bar portionof their respective tracks. The bottoms of the doors clear the lower endof the door opening, and a downwardly open channel provided in the loweredge of each door receives roller guides mounted on the 'sill structureto firmly guide the door and restrain it against inward and outwarddisplacement by lateral forces acting on the doors.

1 1 Claim, 9 Drawing Figures PAIENTED APR 1 71973 SHEEI 1 BF 3 INVENTOR-cscu. BAINBRIDGE z-PM ATTORNEY PAIENIED APR 1 1191s SHEET 2 0F 3 2/III/33 FIG3 FIG. 4

INVENTOR. CECIL BAIN BRIDGE m ATTORNEY FIGS PATENTED APR] 7 I973 SHEET 3[IF 3 FIG. 6

FIG.

INVENTOR.

CECIL BAINBRIDGE ATTORNEY 1 SUSPENSION MECHANISM FOR SLIDING DOOIEBACKGROUND OF THE INVENTION A In the past it has been common practice tosuspend the sliding doors commonly used on rapid transit cars fromroller type hangers, the rollers of which ride in channel track meansmounted above each door opening. In order to have a reasonable lifeexpectancy these rollers are usually of substantial diameter, forexample, of the order of three or four inches, and are mounted with aclose fit in the channel track to avoid rattles and side play. As aresult, unless the bottoms of the doors are positioned and guided tohold the rollers centered in their channel tracks there is a tendencyfor the rollers to bind, which prevents free roller movement andincreases wear on the suspension mechanism. Available statisticsindicate that approximately 80 percent of the failures in existingsliding doors of this type occur in the suspension mechanism.

The problem of providing a satisfactory sliding door for a railway typecar is complicated by the fact that since the car body is supported onbolsters located near its ends, the entire car body tends to bowdownwardly toward its center, and the amount of such bowing varies withthe car loading. Such deflection of the car body in the past has causeda bending of the door support tracks, which tends to cause binding ofthe doors and increased maintenance problems.

In use these prior art door mounting structures are subjected not onlyto the wear and tear caused by their constantly recurring opening andclosing at every station stop, but also that caused by the substantialside loads to which they are recurrently subjected, such as thoseimposed by wind, high speed travel, entering and leaving tunnels andoccasional pressure by passengers. All of these factors tend to swingthe door about their suspension tracks as an axis, and in the case ofexisting wheel or roller type hangers fitted closely into channeltracks, they produce destructive forces acting through substantial leverarms.

A companion case, U. S. Pat. application Ser. No. 75,972, filed Sept.28, 1970 is based on a pre-bowing of the track to compensate for varyingloads to which it is subjected in use.

SUMMARY OF THE INVENTION The present invention provides a car doormounting structure wherein a sliding door is suspended by lowfrictionbearing brackets mounted one at each end of the top of the door, eachbracket including an open type linear motion bearing fitted in slidingrelation on a track supported only at its ends, the suspended door beingfree for limited rotative adjustment without binding about the track asan axis.

A primary objective of the invention is to provide a long lived, troublefree, sliding door support means employing door suspension bracketsattached one to each end of the top of each door, and fitted in freesliding relation on a track which is supported only at its ends.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objectives andadvantages of the invention will be apparentfrom the followingdescription and the accompanying drawings, wherein:

FIG. 1 is a somewhat diagrammatic side elevational view of a sidedoorarea of a rapid transit type railway car, portions being brokenaway.

FIG. 2 is an enlarged, fragmentary elevational view of the portion ofFIG. 1 enclosed by the circular arrow 2, portions being broken away. I

FIG. 3 is an enlarged, fragmentary sectional view taken along line 3-3of FIG. 1,. portions of the car body being omitted.

FIG. 4 is an elevational view looking in the directions of the arrows4-4 of FIG. 3.

FIG. 5 is an enlarged, fragmentary, sectional view taken along line 5-5of FIG. 2, and includes portions of the car body not shown in FIG. 2.

FIG. 6 is an enlarged, fragmentary elevational view FIG. 6.

FIG. 8 is a top elevational view of the lower door guide rollers lookingin the direction of the arrows 8-8 of FIG. 7.

FIG. 9 is a diagrammatic sectional view taken along line 9-9 of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS tural door mounting beam 13 andhousing 14 to shield the track 10 and upper portions of the doorssuspended therefrom. The interior of this track housing 14 preferably issubjected to at least a. slight positive pressure from the interior ofthe car to maintain a more or less uniform temperature in the zone ofthe tracks 10a and 10b and to reduce the amount of dust and dirtentering this housing. The illustrative car A has a double wallstructure, at least in the zone of the door openings, with inner wall15, see FIGS. 1, 6 and 7, and outer wall 17, and a pair of sliding doors18 and 19 mounted to move slidably in the inter-wall space 20 betweenopen and closed position. Conventional door actuating means indicated bydiagrammatic links 21 and 22 in FIG. 1 is provided to move the doorsbetween open and closed position.

An aligned pair of the door support tracks 10a and 10b are mounted aboveeach door opening 23, each by an outer end bracket 24, and inner endscrew 25, see

FIGS. l-5. Since the tracks of each pair and their mounting structuresare similar, except that they are reversed end-for-end, only the lefthand one 10a is described in detail. The outer end bracket 24 has alaterally inwardly facing notch 27 therein to receive an outer endportion of a track base 344, which is shaped to fit snugly therein. Ashoulder screw 28 is fitted into a hole provided in the notched portionof the bracket 24 and also into a hole provided in the end portion ofeach track base 34, and a reduced threaded portion of the screw 28 isscrewed into a threaded continuation of the bracket hole to mount theouter end of the track base firmly, but capable of limited pivotaladjustment about the axis of the screw 28. Each outer end bracket 24 hasan integral mounting plate portion 29, see FIGS. 3- 5, extendinginwardly at right angles to the track end portion mounted therein, andoverlies an end plate 30 in the door mounting beam 13 to which it issecured by screws 31, see FIGS. 3 and 5. A peel-off type shim block 32adjusted to required thickness is fitted into any space which may existbetween the bracket 24 and the end plate 30 before drawing down thescrews 31 to secure the bracket to the car body. The holes in thebracket plate portion 29 are so located that the track is spacedoutwardly clear of the beam 13 as indicated by the clearance 33 in FIGS.3 and 5.

The door support track 10a comprises a channel base portion 34 with anintegral, truncated ridge 35 extending lengthwise centrally therein. Agroove 37 is formed in the top surface of the truncated ridge 35, thegroove having a cross sectional curvature to receive a track rod 38 infitted relation therein. The two part track 100 preferably is archedslightly to compensate for sagging under the weight of the doors inaccordance with my U. S. patent application Ser. No. 75,972 filed Sept.28, 1970 and the track rod 38 is of a material and finish recommendedfor the mounting of linear motion ball bearings thereon.

The track rod 38 is fixedly mounted in the ridge groove 37 by aplurality of screws 39, see FIG. 3, inserted in counterbored holesextending transversely through the center of the track ridge 35, screwedinto threaded holes provided radially of the rod 38, and drawn downtight to anchor the rod 38 in its seat 37 on the track ridge 35.

The inner end of the door support track 10a is secured in adjustedposition to the car body beam 13 by the bolt 25, see FIGS. 2 and 5,inserted through a slotted hole 26 provided in the track base 34, andalso through holes provided in an interposed, peel-off type shim plate41 and in the beam 13. When the inner end of the track is in adjustedposition a nut 42 on the inner end of the bolt 25 is drawn down tight toanchor the track end to the car body. Adjustment of the spacing of theinner end of the track base 34 from the car beam 13 is accomplished bypeeling off required shim elements of the shim plate 41 to locate a door18 suspended from the track 10a in a desired, free-running positionbetween the inner and outer car walls and 17. Vertical adjustment of theinner end of the track may be accomplished by loosening nut 42 of thebolt 40 and threadedly adjusting a track support screw 43, which isthreadedly inserted with a close fit in a threaded hole provided in abracket plate 44 secured, as by welding, to the car body beam 13. Theinner end of the track base 34 is notched out and rests by gravity onits associated screw 43 when the nut 42 is thus loosened. Afteradjustment, the nut 42 is again drawn down tight to retain the track inadjusted position.

For suspending the doors 18 and 19 from their respective tracks, a doorsuspension hanger 45 is mounted on each end of the top of each door.Each door hanger 45 has a flat plate portion 47 which is flush mountedin its respective door structure as best shown in FIG. 5, and is securedthereto by machine screws 50, see FIGS. 2 and 5. An integral, upwardlyprojecting hanger portion 51 is of generally C-shape in cross sectionwith generally cylindrical bore 52 into which is fitted a conventional,open type, linear motion ball bearing bushing 53 of the general typedesignated as OPN by Thomson Industries, Inc. of Manhasset, New York,which firm manufactures bearings of this type.

Each bearing 52 is slidably mounted on the rod portion 38 of itsrespective support track 10a with the open portion of each C-shapehanger portion 51 and its respective bearing 53 positioned to receivethe ridge portion 35 of its track base 34 with sufficient clearancetherefrom to permit limited rotative adjustment without binding of thedoor suspended therefrom about the track rod 38 as an axis. Since eachdoor is limited to very slight rotative adjustment about its respectivetrack axis, due to the limited inter-wall space within which the dooroperates, a clearance which will allow free rotative movement of thedoor of a few degrees in each direction from a normal centered positionof the door is adequate.

For positioning the lower end of each door to centered, inter-wallposition, and for guiding the door during its opening and closingmovements, a downwardly open channel member 54, see FIGS. 1, 6 and 7, isincorporated in the bottom of each door and extends endwise somewhatbeyond the outer end of its door. A guide roller support plate 55 ismounted in a recess provided in the door sill structure 57 within thedouble car wall structure just beyond each side of the door opening 23.Each guide roller support plate 55 is secured in adjusted position tothe sill structure 57 by two screws 59 and 59 which are inserted throughtransversely slotted holes provided in the roller support plate 55 andscrewed into threaded holes provided in the sill structure.

A pair of guide rollers 60 and 61 are journaled on posts 62 and 63,respectively, mounted on the support plate 55 and so tilted that theaxes of the rollers 60 and 61 are substantially parallel to themid-plane of the channel 54. Upon loosening the screws 59 and 59 theroller support plate 55 may be adjusted, both angularly and laterally toposition the lower end of the door which it controls in desired freerunning position within its inter-wall space 20, and with the rollers 60and 61in desired pre-loaded relation with opposite sides of the channel54 in which they are mounted. The rollers 60 and 61 preferably are oflong lived material which requires little or no lubrication. The plasticmaterial known as Delrin has been found satisfactory.

The door mounting structure as illustrated and described herein has nowbeen subjected to a test which, except for the vibration of which itwould be subjected in use, is considered the equivalent of thatencountered in actual operation. This test has now exceeded 1,500,000two stroke cycles of opening and closing operation, and is still inprogress, since to date no breakdown or operational difficulty has beenexperienced, no lubrication or other maintenance has been performed, andno wear is noticeable. This test to date has been calculated as theequivalent, in number of cycles, to some forty years of actual operationin service.

Having thus described my invention, what I claim as new and useful anddesire to secure by U. S. Letters Patent is:

1. Linear ball bearing suspension mechanism for mounting a sliding dooron a structure having a door opening therein, and comprising a unifiedtwo part track extending transversely across an upper end portion ofsuch door opening, said track comprising,

a track base portion having a track rod seat extending lengthwisethereof,

a circular track rod portion seated to the base seat,

means securing the track rod portion in seated relation to its seat toform a unified two part track,

track mounting means connecting only each end of the two-part track tothe support structure abovesuch door opening with said track extendinglaterally beyond the door opening a distance of the order of the widthof a door to be suspended from the two-part track,

a door of a size and shape to cover-a selected portion of such dooropening, i

a door hanger of generally C-shape cross section havin g a C-shaped openlinear motion ball bearing bushing mounted therein, therebeing onesaidhanger mounted adjacent each end of the top of the door and fittedin axially rolling engagement on the circular track rod portion, and

guide means acting between the support structure and a lower portion ofthe door for positioning and guiding the door as the latter moves insuspended relation along the circular track rod portion between open andclosed position.

2. Door suspension mechanism as claimed in claim 1 wherein the base seatis a groove shaped to seat the track rod therein.

3. Door suspension mechanism as claimed in clam 1 wherein the meanssecuring the track rod in seated relation to its seat comprises aplurality of screws inserted in counterbored holes provided in the trackbase i and screwed into threaded holes provided in the track rod portionto register therewith.

4. Door suspension mechanism as claimed in claim 1 wherein the trackbase portion is of a channel shape with a truncated ridge extendinglengthwise therein, and the track seat comprises a groove extendinglengthwise in the truncated top surface of the ridge and shaped to seatthe track rod portion therein.

5. Suspension mechanism for mounting a sliding door'on a structurehaving a door opening therein, and comprising i a unified two part trackextending transversely across an upper end portion of such door opening,said track comprising,

a track base portion having a track rod seat extending lengthwisethereof,

said track base portion being of channel shape with a truncated ridgeextending lengthwise therein, said track seat comprising a grooveextending lengthwise in the truncated top surface of the ridge andshaped to seat the track rod portion therein,

a track rod portion seated to the base seat,

means securing the track rod portion in seated relation to its seat toform a unified two part track, track mounting means connecting only eachend of the two-part'track to the support structure above such dooropening with said track extending laterally beyond the door opening adistance of the order of the width of a door tobe suspended from thetwo-part track,

a door of a size and shape to cover a selected portion of such dooropening,

a door hanger mounted adjacent each end of the top of the door andfitted in axially slidable relation on the track rod portion,

each said door hanger comprising a C-shape portion extending clear ofthe top of the door on which it is mounted and having a bore with anopen type linear type bearing mounted therein with the bearing mountedfor free, axial, sliding movement on the track rod portion and the ridgelocated within, and clear of, the end portions of the C-shape hangerportion and theend portions clefining the open portion of the open typebearing, and

guide means acting between the support structure and a lower portion ofthe door for positioning and guiding the door as the latter moves insuspended relation along the track rod portion between open and closedposition.

6. Door suspension mechanism as claimed in claim 5 wherein the bearingis an open type, linear motion ball bearing.

7. Door suspension mechanism as claimed in claim 5 wherein trackmounting means connecting one end of the two part track to the supportstructure comprises a pivotal support with the track free for limitedpivotal adjustment thereon, and track mounting means connecting theother end of the two part track to the support structure comprises abolt extending through aligned holes in one track portion and an elementof the support structure, one of such. holes being slotted, and threadedadjusting means operatively interposed between said other end of thetrack and a support structure element for limited adjustment of thetrack about the pivotal support for said one end of the two' part trackupon freeing said bolt.

8. Door suspension mechanism as claimed in claim 1 wherein said guidemeans comprises a downwardly open channel mounted in the bottom of thedoor, and a pair of rollers mounted on the support structure laterallybeyond the lower end of a door opening for which the door is provided,the rollers being located within said channel with their axes ofrotation parallel to the sides of the channel and perpendicular to thelongitudinal center line of the channel for free rolling, guidingrelation with the sides of the channel.

9. Door suspension mechanism as claimed in claim 8 wherein the guiderollers are mounted in laterally spaced relation on a support plate, andmeans releasably securing the support plate to the support structure forcombined angular and lateral adjustment upon release of said releasablesecuring means, whereby the support plate and the rollers thereon isadjustable selectively laterally to adjustthe lower end of the dooroutwardly and inwardly, and angularly relative to the mid-plane of thechannel in which the rollers are mounted to adjust pre-loading of therollers against opposite sides of the channel.

10. Door suspension mechanism as claimed in claim 1 wherein two of thetwo part tracks are mounted in aligned, relatively end-for-end reversedrelation with door opening, and a separate door is suspended from 7 8the rod portion of each two part track, each door being structure abovesuch door opening with said track of a size to close one half of suchdoor opening when extending laterally beyond the door opening, the doorsare moved convergently into edge-to-edge a door of a size and shape tocover a selected portion engagement with each other toward the adjacentends of such door p and of their respective tracks. a door hanger ofgenerally C shape cross section 11. Linear ball bearing suspensionmechanism for having a linear motion b bearings mounted mounting asliding door on a structure having a door therem, therebemg one 531dhanger'moumed opening h i d comprising; jacent each end of the top ofthe door and fitted in acircular t k r d axially rolling engagement onthe circular track circular track rod mounting means connecting only 10each end of the circular track rod to the support

1. Linear ball bearing suspension mechanism for mounting a sliding dooron a structure having a door opening therein, and comprising a unifiedtwo part track extending transversely across an upper end portion ofsuch door opening, said track comprising, a track base portion having atrack rod seat extending lengthwise thereof, a circular track rodportion seated to the base seat, means securing the track rod portion inseated relation to its seat to form a unified two part track, trackmounting means connecting only each end of the two-part track to thesupport structure above such door opening with said track extendinglaterally beyond the door opening a distance of the order of the widthof a door to be suspended from the two-part track, a door of a size andshape to cover a selected portion of such door opening, a door hanger ofgenerally C-shape cross section having a Cshaped open linear motion ballbearing bushing mounted therein, therebeing one said hanger mountedadjacent each end of the top of the door and fitted in axially rollingengagement on the circular track rod portion, and guide means actingbetween the support structure and a lower portion of the door forpositioning and guiding the door as the latter moves in suspendedrelation along the circular track rod portion between open and closedposition.
 2. Door suspensIon mechanism as claimed in claim 1 wherein thebase seat is a groove shaped to seat the track rod therein.
 3. Doorsuspension mechanism as claimed in clam 1 wherein the means securing thetrack rod in seated relation to its seat comprises a plurality of screwsinserted in counterbored holes provided in the track base and screwedinto threaded holes provided in the track rod portion to registertherewith.
 4. Door suspension mechanism as claimed in claim 1 whereinthe track base portion is of a channel shape with a truncated ridgeextending lengthwise therein, and the track seat comprises a grooveextending lengthwise in the truncated top surface of the ridge andshaped to seat the track rod portion therein.
 5. Suspension mechanismfor mounting a sliding door on a structure having a door openingtherein, and comprising a unified two part track extending transverselyacross an upper end portion of such door opening, said track comprising,a track base portion having a track rod seat extending lengthwisethereof, said track base portion being of channel shape with a truncatedridge extending lengthwise therein, said track seat comprising a grooveextending lengthwise in the truncated top surface of the ridge andshaped to seat the track rod portion therein, a track rod portion seatedto the base seat, means securing the track rod portion in seatedrelation to its seat to form a unified two part track, track mountingmeans connecting only each end of the two-part track to the supportstructure above such door opening with said track extending laterallybeyond the door opening a distance of the order of the width of a doorto be suspended from the two-part track, a door of a size and shape tocover a selected portion of such door opening, a door hanger mountedadjacent each end of the top of the door and fitted in axially slidablerelation on the track rod portion, each said door hanger comprising aC-shape portion extending clear of the top of the door on which it ismounted and having a bore with an open type linear type bearing mountedtherein with the bearing mounted for free, axial, sliding movement onthe track rod portion and the ridge located within, and clear of, theend portions of the C-shape hanger portion and the end portions definingthe open portion of the open type bearing, and guide means actingbetween the support structure and a lower portion of the door forpositioning and guiding the door as the latter moves in suspendedrelation along the track rod portion between open and closed position.6. Door suspension mechanism as claimed in claim 5 wherein the bearingis an open type, linear motion ball bearing.
 7. Door suspensionmechanism as claimed in claim 5 wherein track mounting means connectingone end of the two part track to the support structure comprises apivotal support with the track free for limited pivotal adjustmentthereon, and track mounting means connecting the other end of the twopart track to the support structure comprises a bolt extending throughaligned holes in one track portion and an element of the supportstructure, one of such holes being slotted, and threaded adjusting meansoperatively interposed between said other end of the track and a supportstructure element for limited adjustment of the track about the pivotalsupport for said one end of the two part track upon freeing said bolt.8. Door suspension mechanism as claimed in claim 1 wherein said guidemeans comprises a downwardly open channel mounted in the bottom of thedoor, and a pair of rollers mounted on the support structure laterallybeyond the lower end of a door opening for which the door is provided,the rollers being located within said channel with their axes ofrotation parallel to the sides of the channel and perpendicular to thelongitudinal center line of the channel for free rolling, guidingrelation with the sides of the channel.
 9. Door suspension mechanism asclaimed in claim 8 wherein tHe guide rollers are mounted in laterallyspaced relation on a support plate, and means releasably securing thesupport plate to the support structure for combined angular and lateraladjustment upon release of said releasable securing means, whereby thesupport plate and the rollers thereon is adjustable selectivelylaterally to adjust the lower end of the door outwardly and inwardly,and angularly relative to the mid-plane of the channel in which therollers are mounted to adjust pre-loading of the rollers againstopposite sides of the channel.
 10. Door suspension mechanism as claimedin claim 1 wherein two of the two part tracks are mounted in aligned,relatively end-for-end reversed relation with their adjacent endssubstantially centered over such door opening, and a separate door issuspended from the rod portion of each two part track, each door beingof a size to close one half of such door opening when the doors aremoved convergently into edge-to-edge engagement with each other towardthe adjacent ends of their respective tracks.
 11. Linear ball bearingsuspension mechanism for mounting a sliding door on a structure having adoor opening therein, and comprising; a circular track rod, circulartrack rod mounting means connecting only each end of the circular trackrod to the support structure above such door opening with said trackextending laterally beyond the door opening, a door of a size and shapeto cover a selected portion of such door opening, and a door hanger ofgenerally ''''C'''' shape cross section having a linear motion ballbearings mounted therein, therebeing one said hanger mounted adjacenteach end of the top of the door and fitted in axially rolling engagementon the circular track rod.